We propose to investigate further the mechanism of membrane damage induced by captan, difolatan and folpet in human erythrocytes. We will examine if these pesticides alter the membrane permeability to anions and macromolecules. In order to determine if the observed permeability changes are indeed due to interaction of the pesticides with the sulfhydryl groups of the membrane, the sulfhydryl content of the treated "ghost" membranes will be measured. The ability of the pesticides to disrupt the membrane structure will also be investigated by studying the release of proteins and phospholipids from erythrocyte membranes. The solubilized proteins and phospholipids will be characterized by gel electrophoresis and thin-layer chromatography, respectively. Binding of the pesticides with membrane components, namely proteins and phospholipids, will be studied using C14-labelled chemicals. Ultrastructural alteration in intact red cells and isolated membranes exposed to the pesticides will be examined by electron microscopy. Attempts will be made to characterize the nature of membrane damage in algae treated with captan, difolatan and folpet. The intracellular material released from Chlorella following pesticide treatment will be characterized. Studies will also be undertaken to determine if certain pesticides like halogenated benzonitriles and dinitrobutylphenol can produce membrane-related structural and functional changes in animal cells.